Electrical protective device.



H. W. BROWN.

ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED DEC. 19. 1913.

1,159,892. Patented Nov. 951915.

WiTNESSES! V IN ENTOR ATTORNEY HAROLD V7. BROK VN, 0F LJKACA, AND IVIANUFACT To all whom it may cameo/v2 Be it know that I. HA 0L1) BRO citizen of the jnitetl and of Ithaca, in the county of W State of Yew York. have and useful I iproveznt. tective Dex"; s, of which i The object of in a relay which will determined load. znul whieh w ier loads z.,;..er time while Yersely as the loud.

Electric circuits :1 e usuul such a nianne that. with overloads, the circr r time than with relatively smul.

owever, the nature oi the loaf v circuit uncl the conditions of o; 3 *1 tion make it clesirsblefin some cases. to he (he shape of timeloucl curve whereas an J different shape (l: ,iruhie in other e M x invention is upplicuhle to the protection of such circuits as supply induction root: The excessive currents taken by induct motors in starting, continue. in some case for a minute or so but tl are usually not allowed to continue for u iniich longer period. Consequently, protection should he almost instantaneous wl en y: lost greatl exceeds that which resin l for start the motor. T l the chorac'teri paratively sharp :31 her and horizonta portions. in

provide suco relay and s r invention, 1 provide als means for lIIc'IOflilClllQ lement in its operation should the l .esessar he single figure of the accompanying; drawing is a cliagnunnmtic' View of a circui which is protected by v. relay embodying my invention. s s v My invention, {is shown in 'th accompany ing drawing; comprises a lx lie-ring" e):-

terns]. heatin elements I [131d 11 will cause a '1 flow through :owex'er. ho

:1 Vi their res from that when the provide two heut n 1a relatiu- 1e inner one 4 1 the outer one cessive overload current will flow tlir the current y large the ell to close V6 7 liilerei r of which r h lO-is sufticie willl be oper: and thus oer-i: the coil l lto the load on tl trip the breaker 1e circuit 8 not ppine' of the it will raise iting elements 2 use their resistance irrent to flow throu instantly,

operation bees as well as proportioning of the resistance in operation.

plained. \Vhile the temperature of :the'

outer heating elements 2 and 3 is increasing, a comparatlvely slight change is effected in the temperature of tie heating element 4 because comparatively little of the total current flows through t, but, when the outer elements 2 and 3 are hot, they transmit'heat" l h v co-efiicient, a trip 0011 connected 1n ,SGIIQS to the inner element by conduction throug the body I and by convection through the heats the other and electro-responsive means connected in series with one of the said resistors.

4:. In an. electrical protective device, the

combination with a resistor having arelagtively high temperature 'co-efficient, of a re- ,sistor having a relatively low temperature iwiththe said resistor having thelow temh perature co-eflicient, the resistor having the air. The "reduction in temperature of t e outer elements will be more rapid than that ofthe inner element, when deenergized, be cause of the greater opportunity for heat radiation. The result is that, after the apparatus has operated once, both the outer elements 2 and 3 and the inner element/t are hotter than they were before the first operation. If the relay is properly compensated, the period of operation thesee 0nd time the overload occurs will be approximately the same as the firsttime, andthe minimum current at which it operates will be approximately the same the second time as the first, as will be the third and each successive time, because .both elements have the-same ratio with'respect to time of tion, however, requires a properrelation of the various resistances n the, two'parallel circuits and theproperl radiating surfaces,

a circuit may be made by those skilled 1n the art without departing from the scope of the same as set forth the appended.

claims.

I claim as my invention:

1. In an electrical protective device, the combination with two resistors having relatively difierent temperature gradients, of electro-responsive means in series with one of the said resistors, said resistors being so disposed that one heats the other.

2. An electrical protective device comprising two resistors so disposed that one heats the other, and electro-responsive means operatively, connected to the said resistors.

3. An electrical protective device comprising two resistors so disposed that one To get the proper compensa high I temperature co-eflicient being connected in shunt relation to the circuit comprising the-other resistor and the trip coil and being adapted to heat the resistor having the low temperature co-efiicient. Q

5. An electrical protective device comprising a resistor that becomes heated when in operation, a second resistor connected in parallel with the said first resistor and in heat-conducting relation therewith and tripping means in circuit with the said second resistor. l I

6. In an electric circuit, the combination with a circuit interrupter, and a trip coil therefor, of two 'resistors disposed in heatconducting relation to each; other and Open atively connected to the electric circuit, said trip coil being operatively connected to one of the said resistors.

7. In an electrical protective device, the combination with a resistor that becomes heated when in operation and a second resistor connected in parallel WltllthG said first resistor, said first resistor being adapted to heat the said second resistor of means in" circuit with the said second resistor for f ,controlling an auxiliary circuit.

8. In an electrical protective device, the

combination with two mam resistors d1s-' posed in heat-conducting relation to each other, of an adjustable auxiliary resistor, and a magnet winding, said adjustable auxiliary resistor and the magnet winding being connected in series relation to one of the said main resistors and. the circuit thus-conthe other main-resistor.

In testimony whereof, I' have hereunto subscribed my name this 28th day of November, 1913. i, j

. HAROLD BROWN, Witnesses:

FRED L. CLOCK," i Pnoo'roa.

Gopies 01' this patent maybe obtained for five cents each, by addressing the "Commissioner of Patents Washington, .D. 0/ 1 stituted being connected in shunt relation to i 

